1. Field of the Invention
The present invention relates to biomechanical models, and more particularly to kits for making biomechanical models of lever systems in the body, such as first, second, or third class lever systems, useful for teaching and demonstration purposes as well as complete models of first, second, and third class lever systems.
2. Brief Description of the Art
The study of anatomy, physiology, and kinesiology requires a thorough understanding of the skeletomuscular system. One educational approach to studying and learning the skeletomuscular system is to consider this system as a combination of levers (i.e., bones) and force generators (i.e., muscles) that act together to produce force that moves a resistance force(i.e., a weight). When muscles contract, force is usually applied to bones, resulting in movement or support of the bones. In the skeletomuscular system, the joints function as fulcrums, the bones function as levers, and the muscles produce the force that moves the levers and resistance. The arrangement of levers, resistance, fulcrums, and forces comprise three classes of lever systems depending on the relative position of the components.
In a Class I lever system (also known as a first class lever system), the fulcrum is located between the force and the resistance. An example of this type of lever system is a child's seesaw. The children alternate between being the resistance (weight) and the force across a fulcrum in the center of the seesaw board. An example of a first class lever system in the body is the head and neck. The joint in the neck is the fulcrum, the posterior neck muscles generate the force that pulls down the back of the head, and raises the face.
In a Class II lever system (also known as a second class lever system), the resistance is located between the fulcrum and the force. An example is a wheelbarrow where the wheel is the fulcrum and the person lifting on the handles provides the force. The load, or resistance, carried in the wheelbarrow is placed between the wheel and the operator. In the body, an example of a class II lever system is the foot and ankle when a person stands on his toes. The calf muscles act as force generators and pull the heel (end of the lever) to elevate the foot and the weight of the entire body, with the ball of the foot acting as the fulcrum.
The Class III lever system (also known as a third class lever system) is the most common type of lever system in the body. In this system, the force is located between the fulcrum and the resistance. An example is a person operating a shovel. The hand placed on the handle closest to the blade acts as the force to lift the resistance, such as a shovel full of dirt, and the hand placed near the end of the handle acts as the fulcrum. In the body, an example of a Class III lever system is the action of the biceps muscle (force generator) pulling on the forearm (lever) to flex the elbow (fulcrum) and elevate the hand (resistance).
Biomechanical engineering students, physical therapy students, medical students, allied health students, veterinary students, and sports medicine students must have a good working knowledge of the joints of the body and how they operate. However, learning the large number of muscles, bones, and joints and how they interact can be a difficult task. Various methods have been developed to assist students in learning the biomechanics of the human body. Textbooks, videos, and computer programs offer methods of teaching the interaction between the various components. However, each of these teaching methods has disadvantages.
In the case of textbooks, the motion of the lever systems and the relative placement of the bones and muscles as they move is difficult to S describe in words and diagrams, and the student is forced to view the three-dimensional movement of a lever system in a two-dimensional presentation. Thus, full appreciation of the actual biomechanics of the lever systems of the body is not possible with textual materials.
In the case of videos, motion of the lever systems can be demonstrated and viewed from multiple angles. However, the student does not have the opportunity to interact physically with the demonstration. For example, the student cannot apply resistance to the lever system and measure forces required to move that resistance. Like textual materials, full appreciation of the actual biomechanics of the lever systems in a video presentation is not possible.
Computer programs can offer animated simulations of lever system motion. In addition, some programs can offer application of "virtual resistance" to the animated lever system and demonstrate how that applied "virtual resistance" affects the force needed to move the lever system. However, the student never interacts with a physical object and thus cannot fully appreciate important details of the biomechanics of the lever systems.
Educational three-dimensional models are available for learning various organs of the human body. For example, models of the human brain, eye, ear, jaw, heart, lung, hand, foot, skull, skeleton, and tooth are available commercially. Anatomical models of various other species, such as dog and horse, are also available. However, while such models show anatomical relationships between various organs, they do not show the biomechanics of lever systems, nor do they demonstrate how resistances are handled by the lever systems. Models of human joints have been made with cardboard and rubber bands; however, such models are not suitable for repeated classroom demonstration use, nor are they designed to quantitatively measure the forces required for joint movement.
What is needed in the art is an interactive educational device that offers a three-dimensional demonstration of the various lever systems, as well as the capability to demonstrate both quantitatively and qualitatively how biomechanical variables affect the force required to move the lever system. The present invention provides an answer to that need.